Equity (Narrative) (Details) - USD ($) $ in Thousands, shares in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Feb. 25, 2016
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value (in dollars)		$ 100,000
Share reissuances, treasury stock, value (in dollars)			$ 104,427
Convertible Debt [Member]
Equity, Treasury Stock [Line Items]
Share reissuances, treasury stock (in shares)			6.6
Share reissuances, treasury stock, value (in dollars)			$ 104,400
2014 Share Repurchase Program [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired, value (in dollars)	$ 100,000
2014 Share Repurchase Program [Member] | Common Stock [Member]
Equity, Treasury Stock [Line Items]
Treasury stock acquired (in shares)	5.2
2016 Share Repurchase Program [Member] | Subsequent Event [Member]
Equity, Treasury Stock [Line Items]
Share repurchase program, value of shares authorized to be repurchased (in dollars)				$ 100,000